When the upper extremity of the humerus is fractured, the humerus generally breaks into several pieces, in particular the humeral head, the lesser tuberosity, the greater tuberosity and the humerus shaft. This type of fracture is known as a “four part humeral fracture”. In this case, as there is no blood supply to the humeral head by the tuberosities, a necrosis of the humeral head occurs. Shoulder prosthesis may be used: the anatomical head of the humerus is replaced by an approximately hemispheric prosthetic humeral head; while the other fractured pieces may be set around the humeral stem.
Examples of various patent documents in the shoulder prosthesis area include the following:
U.S. Pat. No. 5,282,865 to Dong relates to a modular humeral shoulder prosthesis for implant in a predetermined position in the natural humerus to replace the natural humeral head of a shoulder joint. The prosthetic implant has a humeral head component including a humeral head member with a spherical bearing surface of predetermined radius extending from an origin to the bearing surface, an undersurface extending in a first direction, an elongate post integral with and projecting in a given direction from the humeral head member, the given direction making a first acute angle with the first direction, and a post portion on the post, and a humeral stem component including a platform having an upper surface, a stem integral with and depending from the platform, the stem extending along a longitudinal axis for alignment generally longitudinally along the natural humerus, the upper surface extending in a second direction making a second acute angle with the longitudinal axis, and an elongate recess in the stem, the recess extending along the stem and including at least a recess portion complementary to the post portion for reception of the post portion within the recess portion in an integrated coupled assembly wherein the humeral head component is affixed to the humeral stem component with the undersurface of the humeral head member confronting the upper surface of the platform when the bearing surface is in the predetermined position to replace the natural humeral head.
U.S. Pat. No. 5,489,309 to Lackey et al. relates to a modular humeral prosthesis that can be custom fitted to a particular patient by interchanging sizes of the various components by a surgeon interoperatively. The prosthesis features a humeral head having a hemispherically shaped outer surface for placement within the glenoid cavity of a human scapula, the head including on its undersurface a recessed center portion having a first cooperating connecting means. The body has a proximal end and a distal end, with the proximal end including an angled platform having a second cooperating connecting means for engagement with said first connecting means, and the distal end having a third cooperating connecting means. The body also includes a plurality of fins. A cylindrical primary stem has a proximal end and a distal end, the proximal end having a forth cooperating connecting means for engagement with said third connecting means, and the distal end having a fifth cooperating connecting means. A cylindrical secondary stem has a proximal end and a distal end, the proximal end having a sixth cooperating connecting means for engagement with said fifth connecting means, and the distal end having a tip for insertion within the medullary canal of a resected human humerus.
U.S. Pat. No. 5,944,758 to Mansat et al. relates to a proximal humeral prosthesis that is designed for treating a fractured humerus. The prosthesis comprises a head corresponding to the humeral head of a patient, and a stem having a proximal end to which the head is mounted. The prosthesis has a central plane coincident with the longitudinal axis of the stem about which it has a mirror axis of symmetry. One, or preferably pair of, projecting ribs are positioned at or near the proximal end of the stem adjacent the head. The projecting ribs are offset in opposite directions relative to the center plane at substantially identical offset angles (e.g., about 20° to about 40°) approximating the greater or lesser tuberosity of the humerus. Also disclosed is a method of treating a fractured humerus with this prosthesis.
U.S. Pat. No. 5,961,555 to Huebner relates to a modular shoulder prosthesis including a head having a semi-spherical articulation surface bounded by an articular margin disposed in an articular plane generally normal to a head axis. The head further includes a backside disposed opposite the articulation surface and separated from the articulation surface by the articular margin. The prosthesis also includes a stem portion with a proximal end and a distal shaft for insertion into a medullary canal along a shaft axis. A coupling structure is adapted to removably attach the head to the stem through motion in the articular plane.
U.S. Pat. No. 6,102,953 to Huebner relates to a shoulder prosthesis having a head and an elongate stem portion including a proximal end connected to the head, a distal section for insertion into a medullary canal of a humeral bone and an alignment section disposed between the proximal end and distal section. The alignment section includes a plurality of reference marks positioned to facilitate placement of the prosthesis in the bone at a previously determined position.
U.S. Pat. No. 6,168,627 to Huebner relates to a shoulder prosthesis having a head and an elongate stem portion including a proximal end connected to the head, a distal section for insertion into a medullary canal of a humeral bone and an alignment section disposed between the proximal end and distal section. The alignment section includes a plurality of reference marks positioned to facilitate placement of the prosthesis in the bone at a previously determined position.
U.S. Pat. No. 6,168,628 to Huebner relates to a shoulder prosthesis having a head and an elongate stem portion including a proximal end connected to the head, a distal section for insertion into a medullary canal of a humeral bone and an alignment section disposed between the proximal end and distal section. The alignment section includes a plurality of reference marks positioned to facilitate placement of the prosthesis in the bone at a previously determined position.
U.S. Pat. No. 6,171,341 to Boileau et al. relates to a humeral prosthesis of such a type that is provided with a rod intended to be anchored in the humeral canal of a patient, a metaphyseal element extending the rod upward and towards the inside, being this metaphyseal element attached at an area of connection to a flange that serves as support for a generally hemispheric cap capable of interacting with the shoulder socket. The area of connection is arranged approximately along a median line of the mentioned flange and the area of connection extends only over a portion of the mentioned median line so as to establish outside of the area of connection, or outside of a portion of the area of connection, a clearance zone for the joining and fusing of the osseous fragments of the metaphysis.
U.S. Pat. No. 6,193,758 to Huebner relates to a shoulder prosthesis having a head and an elongate stem portion including a proximal end connected to the head, a distal section for insertion into a medullary canal of a humeral bone and an alignment section disposed between the proximal end and distal section. The alignment section includes a plurality of reference marks positioned to facilitate placement of the prosthesis in the bone at a previously-determined position.
U.S. Pat. No. 6,334,874 to Tornier et al. relates to a humeral prosthesis including a shaft adapted to be anchored in a medullary canal of humerus, a metaphyseal portion extending upwardly and endwardly from said shaft and being joined at its outer end to a flange which is adapted to support a dome to cooperate with a glenoidal cavity of a shoulder wherein the metaphyseal portion includes an inner part having at least one antero-posterior rib which is structured to provide an anatomical support for humeral tuberosities and which the at least one rib is oriented at an angle of between 45° to 135° with respect to a frontal plane of the prosthesis.
U.S. Pat. No. 6,398,812 to Masini relates to a humeral prosthesis with anatomic attachment areas for tendon or bone. In the preferred embodiment, at least one set of tendontone attachment points are provided along a line, at least a portion of which is divergent with respect to the axis of the stem. One or more sets of attachment points may be further be provided along a line which is substantially parallel to the axis of the stem, resulting in a “T” “L” or “U” shape. Alternatively, attachment points having a changing degree of diversion with respect to the axis of the stem may be provided along a common, curved line. The attachment points may simply be apertures formed through the body of the implant though, in the preferred embodiment, the apertures are provided on raised tabs. An area of bone-ingrowth material may be provided adjacent the attachment points, and may include a separate fastening mechanism such as a threaded hole to receive a screw. A groove may also be provided in any embodiment to receive the biceps tendon. Particularly with respect to fractures, including multi- and ‘four-part’ fractures, means specifically intended for the rigid reattachment of the greater or lesser tuberosities may be provided separately or in conjunction with other sets of reattachment configurations.
U.S. Pat. No. 6,436,144 to Ahrens relates to a shoulder joint endoprosthesis, consisting of a ball joint head and of a stem part which can be anchored in the humerus and has a prosthesis head. The prosthesis head has, on its outer surface, a multiplicity of bores into which pins for locking tubercle fragments can be driven with frictional fit and form fit.
U.S. Pat. No. 6,494,913 to Huebner relates to a system and method for installing a shoulder prosthesis. The method includes removing the original humeral head and shaping the proximal end of the humerus with one or more implements to prepare the humerus to receive the shoulder prosthesis.
U.S. Pat. No. 6,520,994 to Nogarin relates to a shoulder endoprosthesis for fractures of the upper end of the humerus, comprising a humeral stem, adapted to be accommodated in an intramedullary canal of the humerus and provided with multiple longitudinal ribs, and a humeral proximal part, which is suitable to couple to one end of the stem, is provided with a plurality of lateral fins and has, at an upper end, a portion for engagement with a humeral head which is suitable to reconstruct the head of the humerus of the patient.
Patent No. WO95/22302 in the name of Vincent et al. relates to a modular humeral prosthesis (1) for implantation into a humerus of a patient. A removable fracture cap (40) is provided with a shape so as to allow for space between the cap and the glenoid of a patient into whom the prosthesis is to be implanted. A removable humeral head (50) is provided and may be used interchangeably with the fracture cap depending on the condition of the patient's natural humeral head. Caps and heads of differing sizes may be disposed on the proximal humeral component. A modular distal stem extension (20) allows the overall length of the prosthesis to be selectively increased, thereby allowing the prosthesis to be fitted to patients having humeral shafts of differing sizes.
U.S. Patent Application Publication US2003/0014119 to Capon et al. relates to a shoulder prosthesis (5, 32) comprising a humerus rod (9, 39) intended to be introduced into the medullary cavity of a fractured humerus (2), and a roughly hemispherical head (12) which can be secured to the humerus rod and is designed to become lodged in a glene of the shoulder, characterized in that the humerus head (12) can be fixed to the humerus rod in any radial plane with respect to the axis of the humerus rod (9, 39) after the rod (9, 39) has been fixed into the humerus and the shoulder muscles have been fixed to the head.
French Application FR2763501 in the name of Patrick et al. relates to a shoulder prosthesis with modular components—an intramedullary shank (2) and two interchangeable heads (3,4). The shank has an upper end projection (6) and recess (7) which lie in line with the axis of the head after assembly. The projection has a series of equally-spaced peripheral protuberances (8), while the recess is coaxial with the projection, conical in shape and has a small angle of taper. One of the two heads has a central peg (21) and a cavity (22) shaped to engage with the recess and projection of the shank respectively. The other head has an offset peg and cavity which allow the head to be set in a number of different positions, according to the patient's morphology. In addition, the shank has a fin (16) on its outer surface, and its distal portion (2a) is coated with a porous material such as calcium hydroxyapatite, into which the bone cells can penetrate. Design simplicity, allowing more precise fit with smaller range of components.
French Application FR2689758 in the name of Lehuec et al. relates to a humeral shank for a shoulder prosthesis having a reinsertion finn (1a) on the outside of its proximal end, connected to the head by lengthwise and transverse sections which ensure the partial integration of the fin into the general volume defined by the body of the shank (1). The lengthwise connecting section is formed by grooves (1c) on either side of the fin, linking progressively with the body of the shank, while the transverse section is formed by cut-away surfaces designed to reduce the cross-section of the body at the level of the fin. The proximal end of the shank is also equipped with a thrust collar (1g) which is oval in shape, and has a hole (1f) pierced through it.
Among those benefits and improvements that have been disclosed) other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying figures. The figures constitute a part of this specification and include illustrative embodiments of the present invention and illustrate various objects and features thereof.